Preparation of viscous polymers



PREPARATION or VISCOUS POLYMERS Sterling E. Voltz, Brookhaven, Pa., assignor to Sun i] JCompany, Philadelphia, Pa., a corporation of New ersey N0 Drawing. Filed Apr. 6, 1959, Ser. No. 804,108

8 Claims. (Cl. 260683.15)

This invention relates to the preparation of viscous polymers and more particularly concerns a process for polymerizing alpha-monoolefin hydrocarbons having three or more carbon atoms per molecule to form viscous oily polymers which have utility as additives for other oils or as lubricants per se.

In the polymerization of alpha-monoolefins which have three or more carbon atoms per molecule, those in which there is a substituent at the beta position generally are more easily polymerized than straight chain monoolefins or than those which have one or more substituents located other than at the beta position. The present invention is directed to the catalytic polymerization of the more difiiculty polymerizable alpha-monoolefins, i.e. those which do not have a substituent at the beta position, for the purpose of producing viscous oily products.

According to the invention, alpha-monoolefins having the formula RC=CH wherein R is an alkyl radical having 18 carbon atoms, are polymerized by contacting with a dispersion of particles of lead dihalide in combination with an alkyl aluminum dihalide in an inert organic liquid medium. It it has now been found that such dispersions are highly effective catalytic systems for polymerizing the specified monoolefins, or mixtures thereof, to viscous oily products.

In preparing the catalyst system of the present ilnvention a lead dihalide, such as PbC1 PbF PbBr or PbIg, is dispersed in finely divided anhydrous form in an organic liquid reaction medium and monoalkyl aluminum dihalide, e.g. ethyl aluminum dichloride, is added thereto. Any organic liquid which will be inert under the reaction conditions can be used. Preferably, hydrocarbon liquids are employed, for example, hexanes, heptanes, octanes, cyclopentanes, cyclohexanes, benzene, toluene, xylenes, decalin and the like. Nonterminal olefins which will not react under the conditions employed during the reaction can also be used.

The aluminum compound employed in the foregoing catalyst system can be any monoalkyl aluminum dihalide wherein the alkyl group has 1-10 carbon atoms. The preferred compound is ethyl aluminum dichloride; however, its fluorine, bromine or iodine analogues can be used with good results. Other alkyl radicals can be substituted for the ethyl group, for example, methyl, propyl, isobutyl, isooctyl or decyl radicals.

The polymerization reaction is carried out by contacting the above-described catalyst system with the monomeric olefin which can be introduced into the reaction vessel in either vapor or liquid form. The temperature of the system generally should be above 0 C. and may be as high as 150 C. or even higher. As a general rule the rate of polymerization increases as the reaction temperature is increased. The reaction can be conducted under atmospheric pressure if the boiling point of the ice Patented Dec. 20, 1960 2 reaction medium is above the reaction temperature" em} ployed, or an elevated pressure can be employed when the reaction temperature is above the normal boiling point of the reaction medium. If the monomeric olefin charge is a normally gaseo'ut olefin such as propylene, it is advantageous to maintain an elevated 1 pressure in the reactor since this increases the concentration ,ofdis. solved olefin in the reaction mixture and results in increase in reaction rate. During the course of the reaction it is desirable to stir the reaction mixture continuously in order to effect efiicient contact between the reactant and the catalyst particles.

In preparing the reaction mixture the proportions" ofcomponents can be varied widely, and the' rate of reaction will depend to an extenton the proportions-selected. As a general'rule, it is desirable to use a' 'volume ratio of the charge olefin to reaction medium in he range of 0.2 to 5 on a liquidbasis. It is" also desirable that the molar ratio of lead dihalide to the charge olefiii be in the range of 0.0001 to 0.05- and more preferably 0.001 to 0.01, and that the molar'ratio of the aluminum compound to the lead dihalide be in the range of 0.1 to 10 and more preferably 0.2 to 5.. The reaction. temperature selected will dependto anextnt up on'th'e'particiilar olefin to be polymerized but generally will be in the range of 0 to 150 C. and more preferably 50 to C.

The above-described procedure results in the formation of viscous oily polymers which may or may not remain dissolved in the reaction medium depending upon the experimental conditions and the particular monomer used. Upon completing the reaction a polar compound such as methanol is added to the reaction mixture to deactivate the catalyst system. The oily polymer product can be separated from the catalyst and reaction medium by filtration, extraction and/or distillation. The resulting product can be utilized as a lubricant or can be used to thicken other oils and improve viscosity index. It can also be blended with other materials, for example, petroleum wax, to impart desirable characteristics. The products of the invention can, if desired, be hydrogenated before final use in order to eliminate terminal unsaturation.

The following examples illustrate the invention more specifically:

Example I An inert reaction medium consisting of n-heptane was charged to a reaction vessel and finely divided anhydrous PbCl was added thereto in a molar proportion of one part to 100 parts of the hereinafter specified olefin monomer. Ethyl aluminum dichloride was then added to the mixture in a molar proportion to the PbCl of 3:1. The mixture was heated while being stirred until a temperature of 50 C. was reached. The charge olefin, 4 methylpentene-l, was then added in a volume amount equivalent to the n-heptane and the mixture was stirred for 24 hours with the temperature being maintained at about 50 C. Methanol was then added, the mixture was filtered to separate catalyst particles and the filtrate was distilled to remove the n-heptane and methanol. A viscous oily product was obtained in a yield of roughly 30% by weight based on the 4-methylpentene-1 charged to the system.

A higher yield of viscous polymer product can be obtained by operating in the above manner but employing a higher reaction temperature, e.g. by employing a temperature of 100 C. while maintaining the system under pressure.

Example 11 Three other polymerizations of 4-methylpentene-1 were carried out in the manner described in Example I except that anhydrous PbF2, PbI and PbBr respectively, were substituted for the PbCl the conditions otherwise being the, same. Substantially the same results were obtained in each case.

' By wayof comparison, when any of the lead dihalides is employed in combination with aluminum triethyl in place of ethyl aluminum dichloride, substantially no polymerization of the 4-methylpentene-l is obtained.

The polymerization of other alpha-olefins having 3-10 carbon atoms and which do not have any substituent in the beta position can be carried out in the manner above described with substantially similar results. For example, alpha-olefins such as propylene, butene-l, 3- methylbutene-l, 3-ethylbutene-1, pentene-l, hexene-l, ,4-methylpentene-l, 3,4-dimethylpentene-1, octene-l, vinylcyclohexane, 4,4-dimethylpentene-1, decene-l and S-ethyl- 4,4-dimethylhexene-1 can be polymerized in accordance with the invention to yield viscous oily polymers.

I claim:

1. Polymerization method for forming viscous polymers which comprises contacting, under polymerizing conditions including a temperature in the range of l50 C., an alpha-monooleiin having the formula H H RC=CH wherein R is an alkyl radical having 1-8 carbon atoms,

with a dispersion in an inert organic liquid medium of a lead dihalide in combination with an alkyl aluminum dihalide, the molar ratio of alkyl aluminum dihalide to the lead dihalide being in the range of 0.1-l0.

2. Method according to claim 1 wherein said lead halide is PbCl 3. Method according to claim aluminum dihalide is a dichloride.

4. Method according to claim 3 wherein said alkyl aluminum dihalide is ethyl aluminum dichloride.

5. Method according to claim 1 wherein the polymerizing conditions include a temperature in the range of -100 C.

6. Method according to claim 5 wherein said alphamonoolefin is 4-methylpentene-1.

7. Method according to claim 6 wherein the alkyl aluminum dihalide is ethyl aluminum dichloride.

8. Method according to claim 1 wherein said molar proportion is in the range of 0.2-5.

1 wherein said alkyl Kraus Nov. 12, 1940 Freimiller et a1. Mar. 19, 1957 

1. POLYMERIZATION METHOD FOR FORMING VISCOUS POLYMERS WHICH COMPRISES CONTACTING, UNDER POLYMERIZING CONDITIONS INCLUDING A TEMPERATURE IN THE RANGE OF 0-150* C., AN ALPHA-MONOOLEFIN HAVING THE FORMULA 